Explicitly terminate process in sigterm_handler

[nskool]

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Issue #, if available:

Description of changes:

Just removing socket in sigterm_handler does not seem to kill the process. If a socket gets closed, the STREAM session detects the closing of connection and that should automatically kill process, however, this does not seem to work as expected and we can try explicitly terminating the process in the handler, after removing the socket.

Testing done:

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